Profile

Manatees are large, cylindrically shaped mammals, with forelimbs
modified in to flippers, no free hindlimbs, and the rear of the body in the form of
a flat, rounded, horizontal paddle. The flexible flippers are used for aiding motion over the bottom, scratching,
touching and even embracing other manatees, and moving food into and cleaning
the mouth. Its upper lip is modified into a large bristly surface, which is
deeply divided. It can move each side of the
lips independently while feeding. The general coloration is gray.

The West African manatee weighs less
than 500 kg (1100 lb). Adults are generally 3 - 4 m (10 - 13') long. It inhabits coastal areas, estuarine lagoons, large rivers
that range from brackish to fresh water, freshwater lakes and the extreme
upper reaches of rivers above cataracts.
This manatee species is dependent on emergent or overhanging, rather than submerged,
vegetation. Populations in some rivers depend heavily on overhanging bank
growth, and those in estuarine areas feed exclusively on
mangroves. Seasonal movements in response to changes in water level affecting
availability of food and/or water salinity have been reported in several
areas. An individual manatee may travel 30 - 40 km/day (19 - 25 mi/day) through lagoons and
rivers.

The West African manatee occurs from southern
Mauritania to Angola; its numbers continue to decrease.
The population decline has been attributed largely to hunting and incidental
capture in fishing nets. Despite legal
protection, the manatee is still hunted throughout its range. It is sometimes also killed in turbines or
control gates of dams. The coastal wetlands that
are a major habitat for the manatee have already been heavily damaged and are
further severely threatened. Woodcutting is resulting in the
extermination of mangrove stands in
some areas. Mangrove clearance, as
well as erosion due to forest clearance upstream, are resulting in
increased sedimentation that silts up lagoons and estuaries.

Tidbits

*** By some writers the animal is said to leave the water entirely, and to
search for its food upon the land, but this assertion is now ascertained to be
incorrect (Wood 1860).

*** The West African manatee is the most
threatened of all manatee species (Perrin
2001).

*** The manatee does not have incisors or canine teeth, only cheek teeth
(molars). Molars designed to crush vegetation form continuously at the back of
the jaw and move forward as older ones wear down. The older ones eventually fall out, while new ones
come in at the rear of the jaw to replace them.

*** The three species of manatees, and the closely related dugong, are unique
in that they are the only plant-eating marine mammals in modern times.

*** The West African manatee is protected by national law in every country in which it occurs,
although ineffectively in most areas. Awareness of the protected status of the
manatee is widespread in all areas surveyed, but there is little perceived fear
of arrest and punishment. (Perrin
2001)

There are three species of manatees: the Amazonian manatee
(Trichechus inunguis), the American manatee
(Trichechus manatus), and the West African manatee (Trichechus
senegalensis). The West African manatee is externally indistinguishable from the
American manatee. On the other hand, both the American and West African
manatees can easily be distinguished from the Amazonian manatee,
because they lack the distinctive white markings on the abdomen or chest which
are characteristic of the latter species.

Population Estimates and Status:

[Except where indicated, the following entries are based on Perrin
2001.]

2001: Guinea-Bissau at one time was considered to be one of the last
sanctuaries of the manatee, because of the relatively undisturbed state
of its mangroves, wetlands and river systems. Information on its status
is scarce.

Distribution:

Currently, the West African manatee occurs in most of the coastal marine waters, brackish
estuaries, and adjacent rivers along the coast of West Africa from southern Mauritania
(16° N) to the Loge, Dande, Bengo and Cuanza Rivers, Angola
(18° S). Centers of
population appear to be Guinea-Bissau; the lagoons of
Côte d'Ivoire; the lower
reaches of the Niger River, Nigeria; Sanaga River,
Cameroon; coastal lagoons of Gabon
and the lower reaches of the Congo River. (IUCN
2006)

The West African manatee ascends most major rivers within its range until a cataract or shallow
water prevents its progress. In some rivers, such as along the Benue River, it seeks refuge during the dry season in permanent lakes that communicate
with the rivers during high water but are cut off when river waters subside. The
West African manatee can be found 75 km (47 mi) offshore among the shallow coastal flats and
mangrove creeks (with abundant seagrasses and calm water) of the Bijagos
Archipelago of Guinea-Bissau as well as Casamance
(Senegal). Isolated
populations cut off from the sea are found in Lake Volta, Ghana
above the Volta
hydroelectric dam. An additional population, essentially landlocked above the
major rapids, is found in the upper reaches of Niger River in the inland delta
of Mali as far as Segou, which is the
farthest inland record for this species, over 2,000 km (1200 mi) from the ocean. The West African
manatee is landlocked in the Logone and Chari Rivers of Chad.
It occurs along the entire length of the Gambia River, penetrating into Senegal
where there are records as far upstream as Niokola Koba National Park. In Chad,
this manatee is present in Lake Léré and Lake de Tréné along the Mayo-Kebbi,
Bahr Keeta and Baningi Rivers. The West African manatee is also reported from
the Baningi, Logone and Chari Rivers, tributaries of Lake Chad. (IUCN
2006)

Threats and Reasons for Decline:

In the past, the West African manatee's population decline has been attributed largely to hunting and incidental
capture in fishing nets. Recently, continuing uncontrolled and likely unsustainable
hunting is considered the major threat. Despite legal
protection, the manatee is still hunted throughout its range for meat, leather
and oil, by harpoon, trap, net, and snagline. The few historical data that exist
indicate decreases in catch rates - an indication of a decline in the population.
The West African manatee is viewed as a pest in some
agricultural and fishing areas. It purportedly consumes rice and other crops in the fields and eats small fish caught in gillnets.
This can result in the manatee being killed. This manatee is known to die incidentally in shark nets,
trawls,
set nets and weirs. It is sometimes also killed in turbines or
control gates of dams. The coastal wetlands that
are a major habitat for this manatee have already been heavily damaged and are
further severely threatened. Woodcutting, especially of the red mangrove, for firewood and furniture construction is resulting in the
extermination of mangrove stands in
some areas. Mangrove clearance, as
well as erosion due to forest clearance upstream, are resulting in
increased sedimentation that silts up lagoons and estuaries. Reduced water flow
due to construction of dams reduces availability of estuarine freshwater and
increases overall salinity that affects growth of vegetation. (Perrin
2001)

The level of threats, particularly hunting and incidental catches, appears to
be continuing to increase throughout the West African manatee's range, with
locally high rates and near extirpation in
some regions. (IUCN
2006)

Habitat:

The West African manatee inhabits coastal areas, estuarine lagoons, large rivers
that range from brackish to fresh water, freshwater lakes and the extreme
upper reaches of rivers above cataracts.
This manatee also inhabits the lakes
in these river systems. The basic requirements are - sheltered water with access
to food and fresh water. It can be found in marine
habitats where there is relatively calm water and a source of freshwater. For
example, in Senegal, Gambia,
and Guinea-Bissau, the West African
manatee is attracted to freshwater seeps or springs that are found in marine
habitats. The West African manatee can travel freely between saltwater and
freshwater.

The preferred coastal habitats of the West African manatee are: a) coastal lagoons
with abundant growth of mangroves or
herbaceous growth; b) estuarine
areas of
larger rivers with abundant mangroves in the lower reaches and
grasses further upriver; and, c) shallow (less than 3 m (10') depth) and protected coastal areas with fringing
mangroves or marine aquatic plants. Where river levels fluctuate seasonally,
preferred areas are those with access to deep pools or connecting lakes for
dry-season refuge, and with seasonal flooding into swamps or forests with
abundant grasses and sedges. The
West African manatee may be limited to waters of 18° C
(64° F) or higher. (Perrin
2001)

Birth Season:

The breeding period is uncertain and may last throughout the year, as is
the case with the Amazonian and American
manatees.

Birth Rate:

Usually one calf is produced.

Diet:

The West African manatee feeds primarily on vegetation. It is dependent on emergent or overhanging, rather than submerged,
vegetation. Populations in some rivers depend heavily on overhanging bank
growth, and those in estuarine areas feed exclusively on
mangroves. In Sierra Leone, manatees
supposedly remove fish from nets and consume rice in such quantities
that they are considered to be pests. (Nowak 1999) In Senegal
and Gambia, shell remains of mollusks
have also been found in their stomachs. (IUCN
2006)

An adult might be expected to consume about 8000 kg (17,600 lb) of aquatic vegetation in one
year (Husar 1978).

Behavior:

The West African manatee feeds principally at night and travels in the late
afternoon and at night. It usually rests during the day in water that is 1 - 2
m (3 - 6') deep, sometimes in the middle of a watercourse or hidden in
mangrove roots or under natant vegetation. It makes little disturbance in the
water while swimming. (IUCN
2006)

Seasonal movements of the West African manatee, in response to changes in water level that affect
availability of food and/or water salinity, have been reported for several
areas (Perrin
2001). In Sierra Leone, it was reported that
this manatee is present in the main river
channels year-round, but that a migration of some sort may take place, with an
influx of new animals arriving in most upriver areas as flooding begins in June
and July (Reeves
et al. 1988).